Sound reproducer



May 6, 1930. 1.. E. B'ALTZLEY 1,757,107

SOUND REPRODUCER Filed March 24, 1926 3 Sheets-Sheet 1 ATTORNEY y 1930.L. E. BALTZLE IY 1,757,107

SOUND REPRODUCER Filed March 24, 1926- 3 Sheets-Sheet 2 7 INVENTOR BYx'A ORNY' y 1930- E. BALTZLEY 1,757,107

SOUND REPRODUCER Filed March 24, 1926 3 Sheets-Sheet 3 INVENTOR PatentedMay 6, 1930.

PATENT OFFICE LOUIS E. BALTZLEY, 0] GiLEN RIDGE, NEW JERSEY soum)nnrnonucnn Application filed March 24, 1926. Serial No. 96,967.

The objects of this invention are to reproduce or recreate the musicaland vocal sounds with the greatest possible fidelity and throughout therather wide range of audibility between the low pitched notes at one endand the high pitched notes at the opposite end of the scale ofaudibility.

Various forms of horns, cones andv diaphragms have been designedheretofore which could reproduce well, sounds within a given range orranges, but which because of certain inherent resonant qualities or thelike, lose their ability to translate sounds properly occurring inanother range or ranges. To overcome or reduce these faults orlimitations,

' such extremes have been proposed as topro-.

vide a plurality of horns, cones or the like of different size or shapesand intended to operate in a selective sense, each in its own certainrange or field.

The desired results are attained in the present invention and in asingle unitary device by novel features of construction, combination andrelation of parts, including in one important particular, a mechanicallyor electrically vibrated sound translating member of disc like form andhaving incorporated in 'its structure, circumferentially repetitiouswaves or undulations providing the efliect of substantially radiallyextending ribs which are shallower toward the center and are of greatestdepth toward the rim of the disc. This disc is operated by the centralportion where the undulations are least or possibly entirely absent. Thecentral portion is thus made the most highly sensitive section of thereproducer, capable of responding to the vibrations of the highestorders and the more deeply fluted rim portion becomes the lesssensitivesection, responding to the notes or tones of the lower scales.I

The foregoing and other novel features of the invention will appear morefully as thespecification proceeds.

The drawings accompanying and forming part of this specificationillustrate a few of the possible embodiments of the invention and'it isto be understood that the structure may be varied without departure fromthe spirit and scopeof the invention as hereinafter defined and broadlyclaimed. I

Figure 1 is a broken sectional side elevation of the invention embodiedin -a form of a speaker for radio receiving sets. Figure 2 is anenlarged bottom plan view of the receiving unit.

Figures 3, 4, 5 and 6 are broken part sectional views of different formsof the air vibrating sound wave creating member. Figure 7 is a brokentop plan illustrating one method of guiding or positioning the free edgeof the sound wave member.

Figures 8 and 9 are diagrammatic representations indicative of theoperation under different conditions 1 Figure 10 is a vertical sectionalview of a form of the invention embodied-in a special vertical mount.

Figure 11 is a rear elevation of the same. Thetympanum by whichelectrical vibrations in the receiving unit are converted into sound.

vibrations in the air is designated 7 and isshown in the form of a disccorrugated radially to form radially extending flutes or ribs 8, saidribs being of a minimum height, starting from or near the center of thedisc at 9 and increasing in height and width toward the rim where theyform a Wavy outline at 10 with the successive undulations extending toopposite sides, or to one side only of the general plane of the disc.The effect or result is a series of undulations extending completelyabout the disc, which undulations increase in transverse dimensions orindepth and width radially toward the rim, where plain or fiat portion 11at the center of the disc, whereas in the structures shownin the otherfigures, the flutesstart substantially at Y the center" "of the disc.

These two sets of views serve to illustrate further how the ribs may becurved longitudinally of their extent I so as to produce more or less ofa flare, as indicatedat 12 in Figure 3, be drawn on continuous'straightlongitudinal lines, as shown at 13 in Figures 1 and 4, be curvedfollowing.

the lines of a dome as in Figure 5 or be otherwise shaped.

The actuating connection comprises in the present disclosure, arelatively stiff rod 14 connected usually with the center or centralportion of the tympanum, for instance, by rivetin as at 15 in Figure 1.

Anot er method of connection is to secure the transmitting rod to thecenter of the tym panum by means of a washer or washers 16 at one orboth sides of the central portion, said washers being flat at theircentral portions and fluted at their edge portions at 17 to fit over orembrace the inner ends of the flutes in the tympanum. In this way theinner ends of the flutes are gripped solidly so as to impart a bodilymovement to the t mpanum if the vibrations are of a suflicient y loworder and so that if on the other hand, the vibrations are of asufficiently high order, the inner ends of the flutes will be shiftedwhile possibly the outer ends of the flutes may remain at rest or lag,as indicated respectively in diagrammatic fashion in Figures 8 and 9.This structure and method of connection thus enables the tympanum torespond and recreate both the lower and the higher tone sound waves aswell as those falling within the intermediate range To secure theselective artfully responsive action described, it is desirable to havean actuating unit which will respondpowerfully throughout the range ofaudibility. A unit answering these requirements is illustrated inFigures 1 and 3 and as there shown, consist of a single powerful horseshoe magnet 18 having attached to one polar extremity, a substantiallyU-shaped pole piece 19 with side arms 20 projecting toward the otherpole of the magnet and having attached to said other pole, a similar butlarger pole piece 21 with side arms 22 extending over the pole pieces20.

-Within the gaps 23, 24 between these extensions of opposite polarityare located the magnetic armature heads '25, 26,; which are shownconnected by a hollow core 27 in the center'of which is secured at'28the transmission rod '14.. This rod pro ects freely be through openings29 inlthe outer polar projections and similarly, the armature core promthe inner polar projections20. end ofthe-transmissi'on ro'd'issh'own'tensioned by a s ring 31 to. hold. the armature heatls normal yfloated free of contact in the magnetic gaps. .The actuating winding-forthe unit is shown as a single coil 32 mounted on a hollow spool 33supported and posi- It will be seen that the unit described acts with acombined ush-pull effect at each of the two'gaps an that a. solenoidefi'ect'is exerted upon the armature core lying within the coil andhence the unit is responsive F0 tionatel tioned between the inner polarprojections effects a true reproduction of sound, from the lower rangesof audibility, up through the intermediate ranges to the higher ranges.

The tympanum may be made of different materials and of the samethicknessthroughout or of varying thickness. Thin sheet celluloid andimpregnated pressed buckram of the same thickness throughout have beenfound very satisfactory materials.

The tympanum may be supported entirelyby the transmission link but inthe larger sizes may be supported or guided at the edges with freedomfor bodily vibration after the manner illustrated in igure 7 where it isshown as having notches 34 in the undulated edge of the same receiving aflexible cord 35 which is engaged in the free spaces in the hollowsofthe undulations by supports 36.

he flexible cord '35 which encircles the rim of the tympanum may be usedas a means for bracing the tympanum and making it a more v or less rigidunit. By tightening this cord in the several figures it will be seenthat the overall diameter of the tym anum can be reduced and that thisaction orces the central portion into a conical or arched formation,increasing the rigidityof the device propor- Extra bracing effect can beobtained y increasing the height of the ribs and by extending the'sameclear to or entirely across the center of the disc. Also if desirable,laminations may be-applied to the central or other portions of the discto increase the stiffness or body of the same; The central securingwashers such as shown in Figures 9'and 10 have this effect. Whileusually the tympanum is of circular form, the same may made. in variousother shapes and the claims should be; read with this and the vari- I'ous other considerations above in mind. ects freely through the opemngs30 1plroyided 1 e, ower Figures 10 and 11 illustrate one of thepractical methods of mounting the device. In

these views the tympanum is disposed vertically and supported so byastand-39. This stand carries the actuating unit .and also sectioned ring43 which fits tightly 'overthe rim and the intervening screen material.To, prevent the transmission link "from sagging, said link is shown asextended at 44 past the tympanumsand guided by a bushing 45 aflixed tothe screen material. The transmission rod may slide in this bushing orbe fixed thereto, the flexibility of the screen permitting the latterconstruction. In this case as in the preceding, the tympanum forms asound wave creatingmember which is non-rigid to the more rapid, highertone vibrations and may be substantially rigid so as to follow bodilythe slower lower tone vibrations, the extent of bodily movement varyingwith the rapidity of the sound vibrations.

What is claimed is:

1. In a sound generator, a tympanum having undulations extending fromthe central portion to the rim of the tympanum and gradually increasingin depth and width from such central portion outwardly toward the rimportion of the same and a connection for bodily vibrating said tympanum,said connection being rigidly engaged with an ins termediate portion ofthe tympanum and supporting the tympanum for vibration in free airresponsive to the movements of said connection. 2. In soundreproduction, a tympanum in the form of a disc like structure having anundulatory surface with the undulations thereof gradually increasing inwidth and depth from the central portion toward the rim portion of thestructure, said tympanum being supported for tree bodily movement and anactuating connection rigidly engaged with the central portion of thetympanum.

3. In sound reproduction, a tympanum in the form of a disc likestructure having an undulatory surface with the undulations thereofgradually increasing in width and depth from the central portion towardthe rim portion of the structure, said tympanum being supported for freebodily movement and an actuating connection rigidly engaged with thecentral portion of the tympanum and comprising a flat washer with flutededges engaged with the central portion of the tympanum and atransmission link rigidly engaging with said washer.

4. In sound reproduction, a tympanum of thin disc like form havingradially extending flutes starting from the original flat centralportion of the disc and rising gradually on curved lines to the pointsof greatest magnitude at the rim of the disc.

5. In sound reproduction, a tympanum having an undulatory edge withnotches therein, a flexible supporting connection entered in saidnotches and supports engaged with said connection at'points within thehollows of the undulations.

6. In sound reproduction, a tympanum operating in free unconfined air tocreate selfsustaining sound waves, said tympanum being corrugated toform substantially radial stiffening ribs, the central portion of saidtympanum being more flexible than the rim I portion thereof and anactuating connection rigidly secured to said more flexible inner portionof the tympanum.

7. In sound reproduction, a tympanum operating in free unconfined air tocreate selfsustaining sound waves, said tympanum being corrugated toform substantially radial stiffening ribs, the central portion of said.tympanum being more portion thereof, an actuating connection rigidlysecured to said more flexible inner portion of the tympanum and aflexible connection engaged about the rim of said tympanum contractingthe same and rendering the body of the tympanum more nearly rigid.

8. In sound reproduction, a tympanum for operation in free unconfinedair, said tympanum having an undulatory rim and a tympanum contractingmember engaged with said undulations in the rim.

9. In sound reproduction, a tympanum for operation in free unconfinedair, said tympanum having an undulatory rim,a tympanum contractingmember engaged with said undulations in the rim and positioning membersengaged with portions of said contractible member which span theundulations.

10. In sound reproduction, a tympanum having a rigidly held centralnon-rigid portion and ribs extending substantially radially therefromtoward the rim portion, said ribs increasing in width and depth towardthe rim of the tympanum.

In witness whereof, I have hereunto set my hand this 28th day ofFebruary, 1926.

- LOUIS E. BALTZLEY.

flexible than the rim

